Reaching for the Stars – Affordably
When my son and I flew to Florida to see Atlantis’ final flight, our airline tickets cost us about $6.50 per kilogram (excluding luggage). Sending the space shuttle’s cargo into low Earth orbit cost about $20,000 per kilogram. That huge difference is the major challenge facing spaceflight today. Unless we drastically reduce the cost of reaching orbit, the large-scale exploration and exploitation of space will not occur.
Since Sputnik inaugurated the Space Age, chemical rockets have propelled every payload into orbit and beyond. Their high costs, however, have restricted access to space to those governments, corporations and organizations that can afford millions of dollars to launch a satellite. Consequently, half a century after Sputnik only a few hundred tons of payloads, the equivalent of two 747 freighter flights, reach orbit annually.
Rockets are a remarkable technological accomplishment. What rockets have not done and cannot do is radically reduce the cost of reaching orbit. The problem is not lack of effort. NASA and the U.S. Air Force have spent billions of dollars since the 1980s unsuccessfully exploring rocket-based alternatives such as single-stage-to-orbit and reusable launch vehicles.
Radically reducing costs demands the aerospace industry develop a new approach: ground-based systems (GBS). GBS keeps the engine and most of the fuel on the ground so the spacecraft is almost all payload, not propellant. Like any technology in its formative phase, a range of possibilities exist, including beamed energy propulsion by microwaves or laser beams, space elevators, gas guns and magnetic levitation. GBS should launch hundreds of payloads annually weighing hundreds or thousands of kilograms at a cost as low as $200 per kilogram.
If GBS is so promising, why has it not been developed?
First, although tests have demonstrated proof of concept, GBS technologies remain in the laboratory. On the nine-stage technology readiness levels (TRL) showing how close a technology is to practical application, GBS technologies are at TRL 1 to 2, still in the early stages of proving their practicality and worth.
Second, rockets have fulfilled existing demand adequately. GBS makes economic sense only if demand greatly increases, but demand will increase only if launch costs drop drastically. How can space cargoes expand from the hundreds to thousands of tons annually to justify developing GBS?
Some increase will come from expanding existing services like remote sensing and communications satellites. Low launch costs should attract obvious new markets, like providing propellants, water and other supplies, as well as other demand yet unrealized because current launch costs are so expensive. The 1994 NASA Commercial Space Transport Study report identified 10 potential markets.
The real, radical promise of GBS is creating new markets made possible both by sharply reduced launch costs and the ability to launch thousands of tons annually. Two potential “killer apps” are space-based solar power generation and nuclear waste disposal in solar orbit.
Studies by the U.S. Department of Defense’s National Space Security Office in 2007 and the International Academy of Astronautics in 2011 concluded that constructing a 1-gigawatt solar power station in geosynchronous orbit was technically feasible. Providing environmentally friendly baseload electricity could radically change the world’s energy structure and reduce global warming in the next half-century.
Both studies identified high launch costs as a potentially fatal obstacle. At current costs, launching the solar power station’s 3,000 metric tons would demand $60 billion. Reducing costs an order of magnitude to $2,000 per kilogram would drop launch costs to $6 billion, still a showstopper. Going down to $200 per kilogram means $600 million, a large but feasible quantity.
Safely disposing of nuclear waste has become a political, technical and economic nightmare. The Department of Energy expects to spend approximately $100 billion — roughly $1,400 per kilogram — to dispose of tens of thousands of tons of high-level nuclear waste underground. Space-based disposal is attractive because it not only permanently solves a problem that threatens the future of nuclear energy, but also provides access to funding by shifting the money earmarked for underground disposal to GBS development and deployment.
For GBS to climb the TRL scale and move from the laboratory to a mature functioning system will require a sustained commitment of billions of dollars over many years. The government is the obvious developer, following a long tradition of supporting technologies in their early stages. Indeed, in the decade before Sputnik, the American military invested over $12 billion ($90 billion in 2011 dollars) developing the rockets that propelled the space race of the 1960s.
While costing much less to develop, GBS needs a firm assessment and guide. A template is the 2011 starship study spearheaded by the U.S. Defense Advanced Research Projects Agency (DARPA). DARPA, NASA and the new Advanced Research Projects Agency-Energy should conduct a similar study to assess the possible GBS approaches and establish a roadmap to develop the immature technologies and metrics to compare competing systems. Potential users must participate not only to ensure a fit between future supply and demand but also to generate interest in these new approaches.
The next step would be to invest a few million dollars annually over the next few years to develop these technologies sufficiently to enable a down-select of the most promising approaches. Only then would significant funding be required.
The 2007 National Space Security Office report stated reducing launch costs will have “a transformational, even revolutionary effect on space access.” GBS promises to vastly extend the range of the economically feasible, making the second half-century of the Space Age even more exciting than the first half-century. But first, it must be developed.
Jonathan Coopersmith is an associate professor at Texas A&M University, where he teaches the history of technology.